Chlorinated diphenyl ethers and method of making same



Patented July 11, 1939 UNITED STATES PATENT oer-ice CHLORINATED DIPHENYL ETHERS AND METHOD OF MAKING SAME oarlr. Prutton, Cleveland, Ohio, assignor to The Dow Chemical Company, Midland, Mich., a corporation of Michigan No Drawing. Application June 6, 19st, crial No. 83,976

39 Claims. (01. 260-6l2l This invention relates as indicated to halogenated "diphenyl ethers ,containing combined genated diphenyl ethers and more specifically to chlorine in amounts equivalent to'an average of compounds which, as herein defined, are halomore than two atoms of chlorine per molecule. genated diphenyl ,ethers; halogen-bearing di- I have also been the first to prepare composi-' phenyl ethers; and mixtures of such compounds tions containing compounds in which atleast' and more particularly, 'to the corresponding some of the halogen or more specifically chlorine, chlorine derivatives of diphenylether. Diphenyl instead of being substituted for hydrogen in the ether is sometimes referred to as diphenyl oxide. molecule is added to the molecule without dis- This invention also relates to methods of manplacing hy thus resulting in W a ay ufacture of the above mentioned compositions, be best defined as a halogen addition product 10 which methods are characterized by the fact that resulting from the ha g 0f p y certain compounds previously known are, by the her. f present invention, produced in a more efficient. The above referred to mixtures of-halogenated manner and other compounds new in themselves, I p ylethe s a Characterized by e f not previously made, may be produced thereby. that those containing amounts of'halogen'on the The present application is a continuation-inorder of six or less atoms per molecule are, part of a co-pending application, Serial No. 737,- for the most part, liquids and usually viscous at 070, filed July 26, 1934, in which the aforesaid ordinary temperatures; whereas, those "contain: halogenated diphenyl ether derivatives and prodg n erage of more than six atoms of halonets and methods of making same are disclosed. gen per molecule usually range from semi-solid 20 Halogenated diphenyl ether has usually been resins to crystalline solids. Such mixtures, as prepared in the prior art by the halogenation ve fin may be mixtures f compounds of a solution of diphenyl ether 1. e., diphenyl having different numbers of halogen or more ether dissolved in an inert solvent such, as carp fi a y, Chlor ne atoms per molecule and/or 5 non tet a hl id mixtures containing compounds having the hal- Halogenated diphenyl ether has also: been ogen or chlorine atoms attached to the ring mad i th prior art by th reaction of tw structures in different positions, i. e., isomeric difierent compounds; for example, halogenated mpound Su u e y also de benzene ith a lt of chlorophenol, a mixtures of addition and substitution products It is one of the principal objects of this invenas hereinbefore defined. The manner in which 30 tion, therefore, to provide halogenated or halosuch compounds and mi r may be m facgen-bearing diphenyl ether compounds not me: tlured W l betreated more spe fica y n- Viously il bl nd to provide an improved after'under the description of the process commethod of manufacture of such compounds genprised y y inventionerally, 1 The new polychlorinated diphenyl ether prod- 35 Other objects of the invention will appear as. s ntaining the equivalent of more than two the description proceeds. atoms of chlorine per molecule are mixtures of To the accomplishment of the foregoing an isomeric compounds and other closely related related ends, said invention, then. consists. of compounds which may varysomewhat in chlo- 40 the means hereinafter fully described and P rine content. At room temperature, the mixtures 40 ticlllafly pointeq out in claims; the vary in physical characteristics from viscous oily descrlptlon e h forth in detail certa n al liquids to solidnon-crystalline resins to crystalpmvfed combmatloni of Ingredients embodying line solids as the chlorine content thereof is inmy inventlon, such disclosed means constituting, creased Although individual compounds may 4.1 however, but certain of various forms in which in some instances be separated from such the principle of the invention may be used.

I have been the first to prepare halogenated tures, the mixtures themselves possess charac- (liphenyl ethers containing more than four and teristtcs whic h render 'f Valuable P less than ten atoms of halogen per molecule; ents 1n lubr 1cants, resins, electrical equipment, chlorinated diphenyl ethers containing more than dlelectrlcs p a ng compounds, etc., as 50 three toms f hl i per molewle; liquid hereinafter mentioned. The mixtures containmixtures of halogenated diphenyl ethers cons mor han thr hl atoms p r mole e taining combined halogen in amounts equivalent are especially u e o Such p p es. I to an average of more than four atoms of halo- The relationship b ween the chlorine congen per molecule; and liquid mixtures of halotent of, and average number of chlorine atoms 55 in my chlorinated diphenyl ether products is illultrated by the following table:

Tall-I I Percent 01 Forum by weight ssess-a wqcauoero phenyl ether compound, but maycontain any proportion of chlorine between 39 and 69 per cent by weight, corresponding to the equivalent oimore than three to nearly ten atoms of chlorine per molecule. It should be noted that a composition containing the equivalent of ten atoms of chlorine per molecule, instead of being a mixture of compounds containing difl'erent amounts of chlorine per molecule, will consist substantially of the individual compounds deca chlor diphenyl ether.

Methods of manufacture iodine, iron, metal halides such as the chlorides of iron, aluminum, antimony, bismuth, tin, zinc, etc. and phosphorus tri-chloride to form a series of halogen-bearing products, or more specifically chlorine-bearing products containing up to and including ten atoms of halogen per molecule. By direct halogenation" is meant the process of introducing the halogen by progressive amounts into the diphenyl ether (or partially halogenated diphenyl ether) in the substantial absence of a solvent until the desired degree of halogenation is attained.

Referring now more particularly to the chlorine derivatives of diphenyl ether, it will be noted that prior to my invention, very little was known concerning such derivatives. Diphenyl ether had been chlorinated, in the presence of carbon tetrachloride as a solvent, to produce monochloroand dichloro-diphenyl ether, but no higher chlorination products were obtained. A trichlorodiphenyl ether had also been prepared by diazotizing a monoamino-dichloro-diphenyl ether and reacting the resultant diazonium salt with cuprous chloride in accordance with the well known Sandmeyer reaction. Insoiar as I am aware, no polychlorinated diphenyl ether containing more than three chlorine atoms per molecule had been prepared.

I have now found that polychlorinated diphenyl ethers containing more than three atoms of chlorine per molecule, i. e., above 39 percent of chlorine by weight, may readily be prepared by passing chlorine into diphenyl ether at a temperature sufliciently elevated to maintain the reaction mixture in a mobile fluid condition. I have. further found that the character of the chlorinated product is dependent not only on the extent of chlorination but upon other conditions as well; such as thetemperature at which the chlorination is carried out, whether or not a chlorine carrier is used, the concentration of chlorine in the gas used for chlorination, and the nature of the atmosphere in which the reaction takes place.

When chlorine gas is passed into liquid diphenyl ether (melting point about 27 C.) heat is generated and the temperature may be controlled either by controlling the rate of chlorination or by other means such as cooling or heating coils, jacketed vessels, etc. The rate of heat evolution decreases as the chlorination progresses and as the percentage of chlorine in the produce increases beyond approximately 40% chlorine in the product, depending on the volume of the reaction mass, amount or radiation, etc., it may be necessary to supply heat in order to maintain the desired temperature.

The type of product desired controls the use and type of catalyst, the temperature, and other conditions under which the chlorination is performed. There are, as previously indicated, two general types of reaction products: First, the substitution type or, as previously stated, halogenated diphenyl ethers in which the chlorine atom replaces hydrogen of the original diphenyl ether molecule; and second, the halogen-bearing or addition type in which at least some of the halogen or chlorine adds on to the molecule without displacement of hydrogen. Some of these addition products may be identical with certain chlor-hydro-diphenyl ethers.

The addition type may be converted into the substitution type, with loss of hydrogen chloride by heating to a sufiiciently high temperature,

especially in the presence of chlorine carriers and alkaline materials such as the hydroxides, carbonates, bi-carbonates of sodium, potassium, the alkaline earth metals, etc.

To carry out the chlorination so as to produce a material which consists almost entirely of sub-.

stitution products, it is best to employ a chlorine carrier of the class including iron, iron chloride and aluminum chloride and to maintain the temperature at about 145 C. or higher. A product containing up to about chlorine may be easily prepared in this way. However, by elevating the temperature and preferably by use of an appropriately active catalyst such as aluminum chloride, the chlorine content may be increased up to an amount equivalent to 8 atoms of chlorine per molecule and finally up to the maximum theoretically possible. These products are complex mixtures of chlorine substitution products ranging from the monochlorup to and including nonaor deca-chlor diphenyl ethers.

Any product thus prepared may be iurther refined by treating (optionally at elevated temperatures) with solutions of alkalies, or solid alkalies, alkaline earth oxides, carbonates, etc., to remove free acid and decompose such small amounts of addition products as may be present.

Chlorinated diphenyl ethers prepared as described above, may be further refined by vacuum distillation. Liquids refined from the lowest boiling fractions are relatively fluid and may have very low freezing points. Higher boiling fractions are increasingly viscous until extremely stable waxy or crystalline solids result from the highest boiling fractions. It is possible also to crystallize out certain pure solid constituents such as tetrachlor-diphenyl ether, hexachlor diphenyl ether and others, by chilling and filter- Where it is desired to obtain a maximum amount of addition products when diphenyl be obtained by chlorination by a counterflow process, 1. e., where the flow of liquid is in a direction counter to that of the gas fiow in a single container; or where, in a multiple-container apparatus, the liquid is advanced toward the source of chlorine.

(4) high concentration of chlorine.

In chlorinating diphenyl ether under the conditions just specified, chlorine substitution, as

well as chlorine addition products are obtained. When chlorinated diphenyl ether is prepared so as to contain a substantial proportion of addltion products (e. g. amixture containing about 45% chlorine with about one-fourth of the chlorine in the form of addition products), it is desirable to remove the less stable material by treatment with an alkali. This is conveniently done by heating to a temperature near the maximum temperature to be encountered by the material when in use, with a solid alkaline material such as crushed quick-lime or thehydroxides or carbonates of sodium or potassium, either in the anhydrous state or in the presence of, a small proportion of water.

For most purposes, the diphenyl ether employed in preparing the aforesaid polychlorinated diphenyl ether products need not be pure, but may be of technical grade and contain a small proportion of the usual impurities incident to its manufacture.

Types of apparatus which may be used in the foregoing p ocess The simplest type of apparatus which may be used for chlorination is a single reactor which may be of iron except when it is desired to produce a maximum amount of addition products.

This single reactor may be fitted with internal cooling or heating coils or with a jacket for the same purpose and the operation may be carried out in batch fashion by charging the reactor with diphenyl ether and maintaining the temperature above its melting point while passing chlorine into the reactor at a point near the bottom. The hydrogen chloride generated .by the reaction may be conducted off from the top of the reactor and the temperature controlled as desired by passing a cooling or heating fluid, e. g. water or steam, through the coils or jacket, or by varying the rate *of chlorination.

For more efficient use of the chlorine gas, or to promote the formation of addition products, it may be preferable to have a series of such reactors in which the gas from the top of one reactor is conducted into the bottom of the next. In this 3 erable to use several of such towers connected in series and operated in counter-flow fashion. The temperature control required for the operation of such towers may be obtained by passing the liquid through, a coil which may be heated or cooled as required before conducting it into the f top of the tower.

Examples of the products resulting from the process utilizing two different types of apparatus as described above are as follows:

EXAMPLE I 1 Apparatus Three iron tanks, in series, with gas-input tubes extending to near bottom of each tank.

Temperature Average temperature between 100 and 120 C.

7 Operation I Series of tanks operated in counterflow 'iash-- ion, 1. e., fresh diphenyl ether placed'in tank from which exhaust gas finally withdrawn, (tank #3) and material undergoing final chlorination in tank in which chlorine is introduced (tank #1).

Exhaust gas from tank #1 goes to tank #2, and

exhaust gas from tank #2 to tank #3.

Samples Chlorine Sain lgl'oll lfirmrs Specgic Total in form p e an o c orgrav ay 1: oi addi- No. ination at 88 at 100 F. tion products Second: Percent 2 5 1.094 36, 3. 5 0. 7 2 8% 1.122 38 10.1 1.0 2 12% 1.2)6 45' l4 2 v 4.5 3 18 1.310 150 23. 0 13.8 3 1.384 307 31. 3 10.0 3 32 1. 424 1, 070 41. 5 13.0 3 38 1. 442 1, 090 37. 7 10.7

Alter blowing with air at approx. 150 C.

Exauru 11 Apparatus Iron tower, filled with short sections of iron P1118.

Temperature 1 Approximately 90 C.at top of tower.

' Operation Withdrawn from system at time after start of operation, indicated in table. Results of tests and analyses shown in following table:

- Chlorine Hours of Viscosity Sample Specific Total 111 form of N0. figi gravity 1 689? chlorine addition products Seconds Percent Percent 1 l. 202 46 16. 2 5. 7 2 l. 254 66 22. 5 l0. 3 3% 1. 322 138 29. 5 11.8 4 1.344 245 32. 5 13.0 5 l. 386 755 35. 5 14. 3 6 1. 412 2, 940 37. 5 17. 7

Gaseous chloride was bubbled through 605 grams of diphenyl oxide, contained in a glass reaction vessel, ior 30 hours, at the end of which I time the liduid reaction mixture weighed 1378 1 grams the crease in weight corresponding to a chlorine content of approximately 6 chlorine atoms per molecule of the chlorinated diphenyl ether. reaction mixture so obtained was a liquid at room temperature. The mixture was men heated in glass apparatus to 180 C. Gaseous material, probably hydrogen chloride, was evolved with resultant loss in weight i was heated to and maintained at'approximately of'th'e product. One gram of aluminum chloride was then added to the mixture; the latter 140 Cnand additional chlorine wasp'assed into the same for a period of 23 hours, at'the end of time the increase in weight 1 the mixture indicated the same to have a orine content corresponding to approximately 8 chlorine atoms per molecule. The product so obtained was a dark-red viscous mass whichwas very soluble in carbon tetrachloride and ethyl ether, fairly soluble in. ethyl alcohol but insoluble in water.-

. Exmu IV 'additional aluminum chloride was added in portions to the mixture.

The chlorination was continued until the mass -ibecame nearly solid. At the close of the chlorination, the reacted mixture weighed 1274 grams.

thelncrease in weight corresponding to a chlorine content of approximately 9 chlorine atoms per molecule of chlorinated diphenyl ether. The product was, at room temperature, a dark solid resembling pitch in texture. It was heated in a current of air whereby a crystalline material melting at approximately 313 C. was separated in the form of needles by sublimation.-

I have also prepared a viscous liquid composi-.

tion, having a chlorine content corresponding approximately to that of tetrachloro-diphenyl ether, by reacting chlorine with diphenyl ether at temperatures in the neighborhood of 80-i20 C.

Use: of the compositions liquid compositions of matter containing three or more atoms of halogen per molecule are particularly useful as di-electric fluids in the electrical uses and as lubricants or lubricant addi-.

tion agents for lubricating uses. For the electrical uses, it is important that the composition be freed of the addition type of reaction product but in'the case of the lubricating use, it may be advantageous to have such addition products present. For the electrical use high stability, low volatility and non-inflammability .are characteristics p by these compositions which are especially desired.

Likewise for lubricating uses, high stability, low volatility and non-inflammability are desirable characteristics and in addition, such compositions may be made to possess high viscosity and high load-carrying characteristics.

Of the solid compositions here described, many chlorinated diphenyl possess a wax-like character making them particularly useful as solid di-electric materials and also;as inert plastic materials for many uses. These solids are also available for many uses including that of improving the properties of other liquids useful in the electric and lubricating fields because 01' their high degree of solubility in most organic liquids. Certain of the liquid and solid compositions are useful as impregnating compounds for the preservation of wood and similar materials, and for water-proofing materials such as strawboard. Other modes of applying the principle of my invention may be employed instead of the one explained, change being made as regards the materials employed in carrying out the process, provided the ingredient or ingredients stated in any of the following claims or the equivalent of such stated ingredient or ingredients be employed.

I, therefore, particularly point out and distinctly claim as my invention:

1. As a composition of matter, chlorinated diphenyl ethers having a combined chlorine content corresponding to an average of more than three atoms of chlorine permolecule.

2. Chlorinated diphenyl ether containing more than three atoms of combined chlorine per molecule.

3. Chlorinated diphenyl ether containing more than three and not more than eight atoms of combined chlorine per molecule.

4. Chlorinated diphenyl ether containing from four to ten atoms of combined chlorine per molecule.

5. As a composition of matter, a mixture of chlorinated diphenyl ethers containing an amount of combined chlorine equivalent to an average of more than two atoms of chlorine per molecule.

6. As a composition of matter, a mixture of chlorinated diphenyl ethers consisting largely of chlorinated diphenyl ethers having at least three atoms of combined chlorine per molecule.

'7. As a composition of matter, a mixture of ethers containing an amount of combined chlorine equivalent to an average of at least three and not more than eight atoms of combined chlorine per molecule.

.8. As a composition of matter, chlorinated diphenyl ethers containing from 39% to 69% chloi'ine by weight.

9. As a composition of matter, a mixture of chlorine-bearing diphenyl ethers containing from 39% to 69% chlorine by weight.

10. As a composition of matter, a molecularly heterogeneous mixture of chlorinated diphenyl ethers containing an average of more than two atoms 01 chlorine per molecule with the chlorine of different constituent compounds connected to the ring structure in different positions.

11. As a composition of matter, a molecularly heterogeneous mixture of chlorinated diphenyl ethers containing an average of more than two atoms of chlorine per molecule with the molecules of different constituent compounds containing a different number of chlorine atoms.

12. As a composition of matter, a molecularly heterogeneous mixture of chlorinated diphenyl ethers containing an average of more than two atoms of chlorine per molecule and including a plurality of compounds respectively having the chlorine attached to the ring structure in different positions and containing a different number of chlorine atoms per molecule.

13. As a composition of matter, a mixture of through liquid diphenyl ether in the absence of a solvent.

. 15. The-method of makingv chlorinated diphenyl ether which comprises passing chlorine through liquidfdiphenyl ether in the presence of a catalyst and in the absence of a solvent.

16. The method of making chlorinated diphenyl ether which comprises passing chlorine through liquid diphenyl ether in thepr'esenc'e of.

a catalyst'of the halogen-carrier type and in the absence of a solvent. 7 c

17. The method, ofhmaking chlorinated diphenyl ethers which comprises passing-chlorine through liquid diphenyl ether in the presence of a catalyst. of the halogen-carrier type and in the absence of a solvent andthen refining such product by treating'the samewith an alkali.

' 18. A chlorinated diphenyl ether composition pi'eparable by reacting chlorine with diphenyl ether at temperatures of 145 C. and above, and

' having a combined chlorine contentcorresponding to an average oi more than two atoms of chlorine per molecule.

19. Chlorinated diphenyl ether, preparable by reacting chlorine with diphenyl ether at a temperature above 145" C., and containing combined chlorine in a proportion representing more than three chlorine atoms per molecule.

20. The method which comprises reacting chlorine with diphenyl ether at a temperature of at least 145 C. to form a chlorinated diphenyl ether mixture having a chlorine content corresponding to more than two chlorine atoms per molecule.

21. The method which comprises reacting chlorine with a compound selected from the class consisting of diphenyl oxide and lower chlorinated diphenyl oxides, at a temperature above about 145 C. and in the presence of a halogenation sponding approximately to that of hexachloro diphenyl oxide.

23. Chlorinated diphenyl oxide, preparable by reacting chlorine with diphenyl oxide at an ele- .vated temperature sufficient to maintain the reaction mixture in a mobile fluid condition, and

. having a chlorine content corresponding to more than 4 and lessthan 10 atoms of combined chlorine per mol of chlorinated diphenyl oxide.

, 5 24. The method which comprises reacting diphenyl oxide with chlorine at an elevated temperature sufiicient to maintain the reaction mixture in a mobile fluid condition to form agehlorinated diphenyl oxide mixture haying a chlorine content corresponding to more than four and less than ten atoms of combined chlorine per mol of chlorinated'diphenyl oxide.

25. The method which comprises reacting diphenyl oxide with chlorine at an elevated temperature suflicient to maintain the reaction ture in a mobile fluid condition, andheating the reaction mixture to a temperature suflicient substantially to decompose chlorine addition products, to form a chlorinated diphenyl oxide mixture having a chlorine content corresponding to more than four-and less than ten atoms of combined chlorine per mol of chlorinated diphenyl oxide.

26. The method which comprises reacting diphenyl oxide with chlorine, in the presence of a chlorination catalyst and at an elevated temperature sufficient to maintain the reaction mixture in a mobile fluid condition and substantially to prevent'formation of chlorine addition compounds to form a chlorinated diphenyl oxide mixture having a chlorine content corresponding to more than four and less than ten atoms of combined chlorine per mol of chlorinated diphenyl oxide. v

- 27. The method which comprises reacting diphenyl oxide with sufiicient chlorine at an elevated temperature sufficient to maintain the reaction mixture in the mobile fluid condition to form a chlorinated diphenyl oxide mixture having a. chlorine content corresponding to more than four and less than ten atoms of substituted chlorine per mol of chlorinated diphenyl oxide, heating the reaction mixture to a temperature suflicient substantially to decompose chlorine addition products, removing hydrogen chloride from the reacted mixture, and distilling the latter.

28. The-method which comprises reacting chlorine with diphenyl oxide at a temperature above about 145 C., and in the presence of a chlorination catalyst, to form a chlorinated diphenyl oxide mixture having a chlorine content corresponding to more than four and less than ten atoms of combined chlorine per mol of chlorinated diphenyl oxide.

. 29. A. liquid chlorinated dip-henyloxide composition having a chlorine content of approximately 40 to 51 per cent.

30. A chlorinated diphenyloxide composition, preparable by reacting chlorine with diphenyloxide at an elevated temperature sufficient to maintain the reaction mixture in a mobile fluid condition, andhaving a chlorine content corre-- sponding approximately to that of heptachlorodiphenyloxide.

CARL F. PRU'ITON. 

